This works surprisingly well! I especially like it in apps like Messages and Finder (try holding shift to see the hierarchy of the UI). It's also a good measure of site accessibility when used in the browser. Cool!
I always thought that one of the main UI advantages of Windows vs. OSX is the keyboard control (at least until Microsoft made it a lot worse with the introduction of the Ribbons). This might be a very cool addition to OSX! Keep at it, this has IMO a potential market similar to better touch tools.
This is awesome! I use Vimium, an extension for Chrome that does something similar, but have always wanted to be able to use my keyboard for the entire OS. <a href="http://vimium.github.com/" rel="nofollow">http://vimium.github.com/</a>